Add switch template
Add ejs dependency
Use template to generate sitch configuration file
Save switch configuration file in laboratory directory
Change message in switch configuration script
Destroy netkit node
Set the same name to the virtual machine.

Namae should be unique and remain the same among different executions along
the time
Provide config so that nodes can be destroyed even in error cases
Not to configure switch interfaces if it has not got any
Add template to configure laboratories
Use laboratory template to configure the workspace
Use generic render to manage templates
Add script template to halt virtual machines
Generate halt script from a template